Field of the Invention
The present invention relates generally to microchips and systems and devices employing microchips.
Description of Related Art
Quilt packaging is a new paradigm for inter-chip electrical communication. In quilt packaging conducting nodules that protrude from the vertical facets of integrated circuits are used for a dense, enhanced speed, and reduced-power interface between multiple dies within a package. See, e.g., G. H. Bernstein, Q. Liu, Z. Sun, and P. Fay, Quilt-packaging: a new paradigm for inter-chip communication; Proc. IEEE 7th Electronics Packaging Technology Conference, 2005, pp. 1-6; U.S. Pat. Nos. 7,612,443 and 8,623,700; and co-pending U.S. patent application Ser. No. 14/090,993, filed on Nov. 26, 2013, all of which are incorporated herein by reference. Quilt packaging can not only address the issues of communication among integrated circuits (ICs) (one of the major bottlenecks in the development of electronic systems), but can also simultaneously improve multiple parameters of system performance including bandwidth, system size and weight, power consumption and cost. See, e.g., G. H. Bernstein, Q. Liu, M. Yan, Z. Sun, D. Kopp, W. Porod, G. Snider, and P. Fay, Quilt packaging: high-density, high-speed interchip communications, IEEE Trans. Advanced Packaging, vol. 30, no. 4, November 2007.
A photonic integrated circuit (PIC) combines the function of several individual photonic components into a single device. For example, a PIC may include a light source, a region designed to enhance the interaction of the generated light with a substance under test, and a detector. While such functions can be achieved with individual components and optical elements such as lenses, integrating these functions into a single device could lead to drastic reductions in the cost, size and complexity of the sensing system.
On-chip integration of a quantum cascade (QC) laser with a passive semiconductor waveguide using the conventional semiconductor processing technique is known. But since the QC laser wafer is very expensive, integrating a waveguide and detector on it is not cost effective and at the same time the detector quality is not optimized.
Unfortunately, quite often the various components of a sensing system cannot all be created from the same material because of physical limitations and costs. In the case of compact low cost on-chip mid infrared detection using a QC laser, it is important to use different wafer material for the waveguide and detector. As a consequence, an integrated system may require components made from several different materials, and thus a method of achieving low loss optical coupling between the individual components is required. Here, a method is presented for joining multiple components into a single device to within the accuracy required for low loss optical coupling.